Stent And Stent Delivery Device

ABSTRACT

In one embodiment according to the present invention, a stent is described having a generally cylindrical body formed from a single woven nitinol wire. The distal and proximal ends of the stent include a plurality of loops, some of which include marker members used for visualizing the position of the stent. In another embodiment, the previously described stent includes an inner flow diverting layer.

RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S. patentapplication Ser. No. 15/247,714 filed Aug. 25, 2016 entitled Stent AndStent Delivery Device, which is a continuation of and claims priority toU.S. patent application Ser. No. 13/843,342 filed Mar. 15, 2013 entitledStent And Stent Delivery Device, which claims benefit of and priority toU.S. Provisional Application Ser. No. 61/667,895 filed Jul. 3, 2012entitled Stent, U.S. Provisional Application Ser. No. 61/618,375 filedMar. 30, 2012 entitled Stent Deployment Device, and U.S. ProvisionalApplication Ser. No. 61/612,158 filed Mar. 16, 2012 entitled StentDeployment System, all of which are hereby incorporated herein byreference in their entireties.

BACKGROUND OF THE INVENTION

All of the following applications are hereby incorporated by referencein their entireties: U.S. Provisional Patent Application Ser. No.61/422,604 filed Dec. 13, 2010 entitled Stent; U.S. Provisional PatentApplication Ser. No. 61/425,175 filed Dec. 20, 2010 entitled PolymerStent And Method Of Manufacture; International Patent Application No.PCT/US2010/061627, International Filing Date 21 Dec. 2010, entitledStent; U.S. Provisional Patent Application Ser. No. 61/427,773 filedDec. 28, 2010 entitled Polymer Stent And Method Of Manufacture 2; andU.S. Nonprovisional patent application Ser. No. 13/003,277 filed Jan. 7,2011 entitled Stent.

The present invention relates to devices for the treatment of bodycavities, such as the embolization of vascular aneurysms and the like,and methods for making and using such devices.

The occlusion of body cavities, blood vessels, and other lumina byembolization is desired in a number of clinical situations. For example,the occlusion of fallopian tubes for the purposes of sterilization, andthe occlusive repair of cardiac defects, such as a patent foramen ovale,patent ductus arteriosis, and left atrial appendage, and atrial septaldefects. The function of an occlusion device in such situations is tosubstantially block or inhibit the flow of bodily fluids into or throughthe cavity, lumen, vessel, space, or defect for the therapeutic benefitof the patient.

The embolization of blood vessels is also desired to repair a number ofvascular abnormalities. For example, vascular embolization has been usedto control vascular bleeding, to occlude the blood supply to tumors, andto occlude vascular aneurysms, particularly intracranial aneurysms.

In recent years, vascular embolization for the treatment of aneurysmshas received much attention. Several different treatment modalities havebeen shown in the prior art. One approach that has shown promise is theuse of thrombogenic microcoils. These microcoils may be made ofbiocompatible metal alloy(s) (typically a radio-opaque material such asplatinum or tungsten) or a suitable polymer. Examples of microcoils aredisclosed in the following patents: U.S. Pat. No. 4,994,069—Ritchart etal.; U.S. Pat. No. 5,133,731—Butler et al.; U.S. Pat. No. 5,226,911—Cheeet al.; U.S. Pat. No. 5,312,415—Palermo; U.S. Pat. No. 5,382,259—Phelpset al.; U.S. Pat. No. 5,382,260—Dormandy, Jr. et al.; U.S. Pat. No.5,476,472—Dormandy, Jr. et al.; U.S. Pat. No. 5,578,074—Mirigian; U.S.Pat. No. 5,582,619—Ken; U.S. Pat. No. 5,624,461—Mariant; U.S. Pat. No.5,645,558—Horton; U.S. Pat. No. 5,658,308—Snyder; and U.S. Pat. No.5,718,711—Berenstein et al.; all of which are hereby incorporated byreference.

Stents have also been recently used to treat aneurysms. For example, asseen in U.S. Pat. No. 5,951,599—McCrory and U.S. Pub. No.2002/0169473—Sepetka et al., the contents of which are incorporated byreference, a stent can be used to reinforce the vessel wall around theaneurysm while microcoils or other embolic material are advanced intothe aneurysm. In another example seen in U.S. Pub. No.2006/0206201—Garcia et al. and also incorporated by reference, a denselywoven stent is placed over the mouth of the aneurysm which reduces bloodflow through the aneurysm's interior and ultimately results inthrombosis.

In addition to flow diversion and occlusion, the present invention canalso be used in applications where high coverage or low porosity isdesirable. For example, when treating carotid artery stenosis with astent, emboli or particulates may be dislodged during stent deploymentor post-deployment dilatation. Since these emboli can become lodged inthe brain and cause a stroke, it is desirable to provide a stent withlow porosity to entrap the particulates. Another application of a highcoverage stent is in areas of the body prone to thrombus formation suchas in coronary bypass grafts (also called saphenous vein grafts or SVG)and arteries and veins in the lower extremities. Since the thrombus candislodge and occlude downstream tissues, it is desirable to deploy ahigh coverage device of the instant invention to cover and/or entrap thethrombus to prevent it from migrating.

SUMMARY OF THE INVENTION

In one embodiment according to the present invention, a stent isdescribed having a generally cylindrical body formed from a single wovennitinol wire. The distal and proximal ends of the stent include aplurality of loops, some of which include marker members used forvisualizing the position of the stent.

In another embodiment according to the present invention, a deliverydevice is described, having an outer catheter member and an inner pushermember disposed in a passage of the catheter. The distal end of thepusher member includes a distal and proximal marker band that is raisedabove the adjacent portions of the pusher member body. The previouslydescribed stent can be compressed over the distal marker band such thatthe stent's proximal loops and proximal marker members are disposedbetween the distal and proximal marker bands on the pusher member.

In one example, the delivery device can be used to deliver thepreviously described stent over an opening of an aneurysm. The aneurysmis preferably first filled with microcoils or embolic material eitherbefore or after delivery of the stent.

In another embodiment according to the present invention, a dual layerstent is described having an outer anchoring stent similar to thepreviously described stent and a discrete inner mesh layer formed from aplurality of woven members. The proximal end of the outer stent and theinner stent are connected together by connecting members or crimping,allowing the remaining portions of the outer anchoring stent and innermesh layer to independently change in length as each begins to expand indiameter. Alternately, the inner mesh layer may only extend along aportion of the length of outer stent and may be symmetrically orasymmetrically positioned between the out stent's distal and proximalends.

In one example, the dual layer stent can be delivered over the openingof an aneurysm to modify the flow of blood that enters the aneurysm. Asthe blood flow into the aneurysm becomes stagnant, a thrombosis forms toblock up the interior aneurysm space.

In another embodiment according to the present invention, a single ordual layer stent can be created by polymerizing a prepolymer liquidinside a tube, syringe or similar structure. Patterns can be created inthe polymer structure via a pre-patterned mandrel on which the polymerstructure is polymerized or by cutting the polymer structure afterpolymerization.

In another embodiment according to the present invention, a dual-layerstent is connected at multiple locations along its length. For example,a tantalum wire can be woven between both layers, maintaining the layersin close proximity to each other. Both layers of the stent may bebraided or woven at the same braid angle (i.e., picks per inch) whichallows both layers to contract in length by the same amount and rateduring expansion.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects, features and advantages of which embodiments ofthe invention are capable of will be apparent and elucidated from thefollowing description of embodiments of the present invention, referencebeing made to the accompanying drawings, in which:

FIG. 1 illustrates a side view of a stent according to a preferredembodiment of the present invention;

FIG. 2 illustrates a front view of the stent of FIG. 1;

FIG. 3 illustrates a magnified view of area 3 in FIG. 1;

FIG. 4 illustrates a magnified view of area 4 in FIG. 1;

FIG. 5 illustrates a magnified view of area 5 in FIG. 1;

FIG. 6 illustrates a magnified view of area 6 in FIG. 1;

FIG. 6A illustrates an alternate view of area 6 in FIG. 1 have two coilsformed by different strands of wire;

FIG. 7 illustrates a side view of a pusher member according to apreferred embodiment of the present invention;

FIG. 8 illustrates a partial cross sectional view of the pusher memberof FIG. 7 having the stent of FIG. 1 compressed over its distal end andbeing positioned in a catheter;

FIG. 9 illustrates the stent of FIG. 1 positioned over the opening of ananeurysm;

FIG. 10 illustrates a side view of a mandrel according to the presentinvention that can be used to create the stent of FIG. 1;

FIG. 11 illustrates a side view of a stent according to a preferredembodiment of the present invention;

FIGS. 12-14 illustrate various views of a dual layer stent according toa preferred embodiment of the present invention;

FIG. 15 illustrates a cross sectional view of a delivery system for thedual layer stent of FIGS. 12-14;

FIG. 16 illustrates a perspective view of dual layer stent having anouter stent layer formed from a tube or sheet of material;

FIG. 17 illustrates a cross sectional view of the dual layer stent ofFIG. 15 showing various optional attachment points of both layers of thedual layer stent;

FIG. 18 illustrates another preferred embodiment of a dual layer stentaccording to the present invention;

FIG. 19 illustrates a stent according to the present invention composedof a flow-diverting layer;

FIG. 20 illustrates a dual layer stent according to the presentinvention having a shortened flow-diverting layer;

FIG. 21 illustrates a dual layer stent according to the presentinvention having an elongated flow-diverting layer;

FIG. 22 illustrates a dual layer stent according to the presentinvention having an asymmetrically positioned flow-diverting layer;

FIGS. 23 and 24 illustrate an expansile wire for use with aflow-diverting layer according to the present invention;

FIG. 25 illustrates a portion of a flow-diverting layer having anexpansile wire incorporated into its structure;

FIG. 26-29 illustrate a process according to the present invention forcreating a polymer stent or stent layer;

FIG. 30 illustrates another process according to the present inventionfor creating a polymer stent or stent layer;

FIGS. 31-36 illustrate another process according to the presentinvention for creating a polymer stent or stent layer;

FIGS. 37-39 illustrate various aspects of a stent delivery pusheraccording to the present invention;

FIGS. 40-50 illustrates various embodiments of stent delivery pushershaving different distal end shapes according to the present invention;

FIGS. 51-59 illustrate various embodiments of a rapid exchange stentdelivery system according to the present invention;

FIG. 60 illustrates another embodiment of a stent delivery pusheraccording to the present invention;

FIG. 61 illustrates another embodiment of a stent delivery pusheraccording to the present invention;

FIGS. 62-66 illustrate another embodiment of a dual layer stentaccording to the present invention; and,

FIG. 67 illustrates another embodiment of a single layer stent havingdifferent sized wires according to the present invention.

DESCRIPTION OF EMBODIMENTS

Specific embodiments of the invention will now be described withreference to the accompanying drawings. This invention may, however, beembodied in many different forms and should not be construed as limitedto the embodiments set forth herein; rather, these embodiments areprovided so that this disclosure will be thorough and complete, and willfully convey the scope of the invention to those skilled in the art. Theterminology used in the detailed description of the embodimentsillustrated in the accompanying drawings is not intended to be limitingof the invention. In the drawings, like numbers refer to like elements.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

FIG. 1 illustrates a stent 100 according to a preferred embodiment ofthe present invention. The stent 100 is woven or braided together from asingle wire 102 to form a generally cylindrical shape with a pluralityof loops 104 around the perimeter of both ends of the stent 100.

As seen in area 5 in FIG. 1 and in FIG. 5, the ends of the single wire102 can be connected to each other via welding (see welded region 116),bonding agents or a similar adhesive mechanism. Once the ends are weldedor bonded, the wire 102 has no “free” ends.

Each of the loops 104 may contain one or more coil members 106.Preferably, the coil members 106 are disposed around the wire 102 of theloops 104 which, as discussed in greater detail below, denote theproximal and distal ends of the stent 100. Additionally, these coilmembers 106 may provide additional anchoring force within a deliverydevice as described in greater detail below.

In one example, a distal end of the stent 100 includes at least twoloops 104 with two coil members 106 each and a proximal end of the stent100 includes at least two loops 104 with one coil member 106 each.However, it should be understood that the stent 100 can include anynumber of coil members 106 on any number of loops 104.

Preferably, these coil members 106 are positioned near a center area ofthe loop 104, such that when the stent 100 is in a collapsed state, thecoil members 106 are positioned near the very distal or very proximalend of the stent 100.

Preferably, each coil member 106 is composed of a wire 105 wound arounda portion of the loop 104. Each coil member 106 can be composed of adiscrete wire 105 (as seen in FIG. 3) or a single wire 105 can formmultiple coil members 106 (as seen in FIGS. 1, 3 and 6). In the presentpreferred embodiment, some coil members 106 are composed of discretesections of wire 105 while other coil members 106 on either end areformed from the same, continuous wire 105. As seen in FIG. 1, the wire105 can connected to coil members 106 on each end of the stent 100 bybeing located within the inner portion or lumen of the stent 100.Alternately, the wire 105 may be woven into the wires 102 of the stent100.

In another embodiment, wire 105 can be composed of two or moreconstituent wire elements which are wound together to produce wire 105.Utilizing two or more twisted wires to create element 105 can increasethe flexibility of wire 105, by lowering the bend radius and thusincreasing the overall curvature/flexibility. Increased flexibility mayaid in collapsibility and trackability of the device.

When multiple wires are wound together to produce wire 105, eachconstituent wire element may individually wind at the proximal anddistal ends of the stent to produce coils 106 in series. Thus one of theconstituent wire elements can be wound to form one coil 106, followed byanother one of the constituent wire elements wound into a subsequentcoil 106.

Preferably, the wire 105 of the coil members 106 is composed of aradiopaque material such as tantalum or platinum. The wire 105preferably has a diameter of about 0.00225″.

Alternately, the coil members 106 may be a radiopaque sleeve that isdisposed on and adhered to the loop 104.

In one embodiment, the loops 104 on the proximal end of the stent 100have one coil 106 on each side of the loop 104 (as seen in FIG. 3) whilethe distal end of the stent 100 includes only one coil 106 on one sideof each loop 104 (as seen in FIG. 6).

Preferably, the weaving pattern of the stent 100 prevents the distalcoils 106 from being exposed or “sticking up” from an outer diameter ofthe stent 100 during retraction. Hence, if the user decides to retractthe stent 100 back into the catheter for repositioning and redeployment,the distal coils 106 will not catch or contact the distal edge of thecatheter, thereby minimizing damage to the stent 100 that mightotherwise occur during retraction.

One specific technique for minimizing the exposure of the distal coils106 during retraction is to weave the stent 100 such that portions ofthe wire 102 overlap (i.e., are positioned at a greater outer diameterposition) than the side of the loop 104 with coil 106. As seen in FIG.6, some smaller, minor loops 107 are woven to overlap a first side 104Aof the loop 104 that includes the coil 106 (see location 109) whileother minor loops 107 are woven underneath a second side 1046 of theloop 104 (see location 111).

As a user retracts the stent 100 back into the catheter, the minor loops107 move inward (i.e., towards the center of the stent's passage) as thestent 100 compresses in diameter, thereby inwardly pressing on the firstside 104A of the loop 104. In this respect, the minor loops 107 exertinward or compressive force on the first side 104A of the loop 104. Thisconfiguration ensures that the first side 104A of the loop 104 andtherefore the coil 106 is not positioned at an outermost diameter of thestent 100 during retraction and therefore reduces the likelihood of thecoils 106 of catching or hooking on to the distal end of the deploymentcatheter.

As seen best in FIG. 1 and FIG. 2, the loops 104 are flared or biased toan outer diameter 114 when fully expanded relative to the diameter ofthe main body of stent 100. These loops 104 can also expand to adiameter that is even with or smaller than that of the main body.

The stent 100 preferably has a diameter 110 sized for a vessel 152 inthe human body, as seen in FIG. 9. More preferably, the diameter 110 isbetween about 2 mm and 10 mm. The length of the stent 100 is preferablysized to extend beyond the mouth of an aneurysm 150 as also seen in FIG.9. More preferably, the length of the stent 100 is between about 5 mmand 100 mm.

FIGS. 7 and 8 illustrate a delivery system 135 according to the presentinvention which can be used to deliver the stent 100. A catheter orsheath 133 is positioned over a delivery pusher 130, maintaining thestent 100 in its compressed position. Once the distal end of the sheath133 has achieved a desired target location (i.e., adjacent an aneurysm150), the sheath 133 can be retracted to release the stent 100.

The delivery pusher 130 is preferably composed of a core member 132,which tapers in diameter near its distal end (made from nitinol). Aproximal area of the tapered end of the core member 132 includes alarger diameter first wire coil 134 that is preferably made fromstainless steel and welded or soldered in place on the core member 132.Distal to the coiled wire is a first marker band 136 that is fixed tothe core member 132 and preferably made from a radiopaque material suchas platinum.

A smaller diameter second wire coil 138 is located distal to the markerband 136 and is preferably made from stainless steel or plastic sleeve.A second marker band 140 is located distal to the second wire coil 138and is also preferably made from a radiopaque material such as platinum.Distal to the second marker band 140 is a narrow, exposed section 142 ofthe core member 132. Finally, a coiled distal tip member 144 is disposedon the distal end of the core member 132 and is preferably composed of aradiopaque material such as platinum or tantalum.

In one example, the inner diameter of the sheath 133 is about 0.027″ andabout 1 meter in length. The delivery pusher 130 is also about 2 metersin length. The sections of the delivery pusher 130 preferably have thefollowing diameters: the proximal region of the core member 132 is about0.0180 inch, the first wire coil 134 is about 0.0180 inch, the firstmarker band 136 is about 0.0175 inch, the second wire coil 138 is about0.0050 inch, the second marker band 140 is about 0.0140 inch, the distalcore member section 142 is about 0.003 inch, and the distal tip member144 is about 0.0100 inch. The sections of the delivery pusher 130preferably have the following lengths: the proximal region of the coremember 132 is about 1 meter, the first wire coil 134 is about 45 cm, thefirst marker band 136 is about 0.020 inch, the second wire coil 138 isabout 0.065 inch, the second marker band 140 is about 0.020 inch thedistal core member section 142 is about 10 cm, and the distal tip member144 is about 1 cm.

As seen in FIG. 8, the stent 100 is compressed over the distal end ofthe delivery pusher 130 such that the coil members 106 on the proximalend of the stent 100 are positioned between the first marker band 136and the second marker band 140. Preferably, the proximal coil members106 are not in contact with either marker band 136 or 140 and aremaintained via frictional forces between the sheath 133 and the secondcoiled area 138.

When the distal end of the delivery pusher has reached an area adjacenta desired target location (e.g., near an aneurysm), the sheath 133 isretracted proximally relative to the delivery pusher 130. As the sheath133 exposes the stent 100, the stent 100 expands against the walls ofthe vessel 152, as seen in FIG. 9.

The stent 100 can also be retracted (if it was not fullydeployed/released) by retracting the pusher 130 in a proximal direction,thereby causing the marker band 140 to contact the proximal marker bands106, pulling the stent 100 back into the sheath 133.

In one example use, the stent 100 can be delivered over the opening ofan aneurysm 150 after embolic devices or material, such as emboliccoils, have been delivered within the aneurysm 150. In this respect, thestent 100 helps prevent the treatment devices from pushing out of theaneurysm 150 and causing complications or reducing efficacy of thetreatment.

In one example, the wire 102 is composed of a shape-memory elasticmaterial such as nitinol between about 0.001 inch and 0.010 inch indiameter.

The wire 102 may also vary in diameter over the length of the stent 100.For example, the diameter of the wire 102 near the proximal and distalends may be thicker than that of the middle portion of the stent 100. Inanother example, the proximal and distal ends may be thinner than themiddle portion. In another example, the diameter of the wire 102 mayalternate between larger and smaller diameters along the length of thestent 100. In yet another example, the diameter of the wire 102 maygradually increase or decrease along the length of the stent 100. In yetanother example, the loops 104 may be composed of wire 102 having alarger or smaller diameter than that of the wire 102 comprising the mainbody of the stent 100. In a more detailed example, the diameter of thewire 102 of the loops 104 may be about 0.003 inch while the wire 102 ofthe body of the stent 100 may be about 0.002 inch.

In yet another example, select areas of the wire 102 may have a reducedthickness where the wire 102 may cross over another section in acompressed and/or expanded configuration of the stent 100. In thisrespect, the thickness of the stent 100 can be effectively reduced incertain configurations. For example, if sections of the wire 102 werereduced at areas where the wire 102 overlapped when in a compressedconfiguration, the overall profile or thickness of the stent 100 can bereduced, allowing the stent 100 to potentially fit into a smallerdelivery catheter.

This variation in diameter of the wire 102 can be achieved byelectropolishing, etching or otherwise reducing portions of theassembled stent 100 to cause a diameter reduction. Alternately, regionsof the wire 102 can be reduced prior to being wound or woven into theshape of the stent 100. In this respect, a desired weaving pattern canbe determined, the desired post-weaving, reduced-diameter regions can becalculated and reduced, and finally the stent 100 can be woven with themodified wire 102.

In another variation, the pre-woven wire 102 can be tapered along asingle direction and woven together to form the stent 100.

In one example preparation, a 0.0035 inch diameter nitinol wire is woundor woven over a mandrel 160. As seen in FIG. 10, the mandrel 160 mayhave three pins 162, 164, 166 extending through each end, such that aportion of each end of each pin extends out from the body of the mandrel160. The wire 102 begins at one pin, and then is wound 3.0625revolutions clockwise around the body of the mandrel 160. The wire 102is bent around a nearby pin, then wound 3.0625 revolutions clockwiseback towards the other side of the mandrel 160, passing over and underthe previously wound section of wire 102. This process is repeated untileight loops are formed on each end.

In another example, the mandrel 160 may have 8 pins and the wire 102 iswound 2.375 revolutions. In another example, the mandrel 160 may have 16pins and the wire 102 is wound 3.0625 revolutions. In yet anotherexample, the mandrel may have between 8 and 16 pins and is wound between2.375 and 3.0625 revolutions.

Once wound, the stent 100 is heat-set on the mandrel 160, for example,at about 500° C. for about 10 minutes. The two free ends of the nitinolwire can be laser welded together and electro-polished such that thefinal wire diameter is about 0.0023 inch.

Finally, the radiopaque wire 105 of about 0.00225 inch in diameter iswound onto different areas of the stent loops 104, forming coil members106. Preferably, the wire 105 is wound for about 0.04 inch in length tocreate each coil member 106.

In another embodiment, the stent 100 can be formed from a plurality ofdiscrete wires instead of a single wire 102. The ends of this pluralityof wires can be left free or can be welded, adhered or fused togetherfor form loops 104. In another embodiment, the stent 100 can be formedby laser cutting, etching, machining or any other known fabricationsmethods.

The wire 102 is preferably composed of a shape memory metal such asNitinol. Optionally, this shape memory metal can include a variety ofdifferent therapeutic coatings or a hydrogel coating that swells orexpands when exposed to blood. The wire 102 can also be composed of abiocompatible polymer material (e.g., PET) or from a hydrogel material.

FIG. 11 illustrates an embodiment of a stent 190 that is similar to thepreviously described stent 100, except that each end of the stent 190includes three loops 104 instead of the four loops 104 of the previousstent 100. Additionally, the radiopaque wire 105 that form each of thecoils 106 is also preferably woven into the stent 190, connecting atleast some of the coils 104 on each end of the stent 190. Finally, thewire 102 is woven back and forth about 12 times along the length of thestent 190.

FIG. 12 illustrates a preferred embodiment of a dual layer stent 200according to the present invention. Generally, the dual layer stent 200includes an outer anchoring stent 100 that is similar to the previouslydescribed stent 100 seen in FIGS. 1-9. The dual layer stent 200 alsoincludes an inner flow-diverting layer 202 that is disposed within theinner lumen or passage of the anchoring stent 100.

Often, stents with relatively small wires do not provide adequateexpansile forces and therefore do not reliably maintain their positionat a target location. Additionally, prior art woven stents created withmany wires can have free ends that can poke or damage a patient'svessel. In contrast, larger wires are difficult to weave tightly enough(i.e., large spaces between adjacent wires) to modify blood flow at adesired location. The stent 200 seeks to overcome these disadvantages byincluding both the larger wire braid anchoring stent 100 to provide adesired anchoring force and the smaller wire braid flow-diverting layer202 to divert blood.

In one example, the flow-diverting layer 202 is composed of at least 32wires 204 that are between about 0.0005 to about 0.002 inch in diameterand made from a memory elastic material such as nitinol. These wires 204are woven or braided together in a tubular shape having a pore size lessthan 0.010 inch. Preferably, this braiding is achieved with a braidingmachine, which is known in the art and can braid the wires 204 in aregular pattern such as a diamond shaped pattern.

The flow-diverting layer 202 can have areas of its wire 204 that have areduced diameter, similar to the patterns and techniques previouslydescribed with regard to the wire 102 of the stent 100. Additionally,the flow-diverting layer 202 can be formed by laser cutting or etching athin tube.

In the present example, the distal and proximal ends of theflow-diverting layer 202 are perpendicular relative to the length of thelayer 202. However, these ends may also be angled relatively to thelength of layer 202 in a matching, opposite or irregular angularconfiguration.

As best seen in FIGS. 13 and 14, the proximal end of the dual layerstent 200 includes a plurality of attachment members 206 that connectthe anchoring stent 100 with the flow-diverting layer 202. Theattachment members 206 can be composed of tantanlum wire (in this caseis 0.001″ dia.) and can be attached to portions of wire 102 and wire202. In another embodiment, the proximal end of the flow-diverting layer202 can be crimped on to the wires 102 of the anchoring stent 100. Inanother embodiment, portions of the stent 100 and flow-diverting layercan be woven through each other for attachment purposes. In yet anotherembodiment, the stent 100 can be formed with eye-loops (e.g., formed vialaser cutting or etching) or similar features sized to allow wires 202to be woven through for attachment purposes.

Since the anchoring stent 100 and the flow-diverting layer 202 may havedifferent weave patterns or weave densities, both will shorten in lengthat different rates as their diameter expands. In this respect, theattachment members 206 are preferably located at or near the proximalend of the anchoring stent 100 and the flow-diverting layer 202 asoriented in the delivery device (i.e., on the end opposite the distaltip member 144). Hence, as the stent 200 is deployed, both the anchoringstent 100 and the flow-diverting layer 202 can decrease in length (orincrease if retracting the stent 200 back into a delivery device), yetremain attached to each other. Alternately, attachment members 206 canbe positioned at one or more locations along the length of the duallayer stent 200 (e.g., at the distal end, both ends, the middle, or atboth ends and the middle region).

In one example embodiment of the stent 200, a flow-diverting layer 202comprises 48 wires with a density of about 145 ppi and fully expands toa diameter of about 3.9 mm. An outer stent 100 comprises a single wirewound in a 2.5 revolution winding pattern and fully expands to adiameter of about 4.5 mm. When both layers 100 and 202 are fullyexpanded, the lengths are about 17 mm and 13 mm respectively. When bothlayers 100 and 202 are compressed on a 0.027 inch region of a deliverydevice, their lengths are about 44 mm and 37 mm respectively. When bothlayers 100 and 202 are expanded within a 3.75 mm vessel, their lengthsare about 33 mm and 21 mm respectively.

In one preferred embodiment of the dual layer stent 200, theflow-diverting layer 202 is composed of wires 204 having a diameterbetween about 0.0005 inch and about 0.0018 inch and the wires 102 of thestent 100 have a diameter between about 0.0018 inch and about 0.0050inch. Therefore, the minimum preferred ratio between the diameter of thewire 102 and wire 204 is about 0.0018 to 0.0018 inch respectively (orabout a 1:1 ratio) and the maximum preferred ratio is about0.0050/0.0005 inch (or about a 10:1).

It should be noted that the dual layer stent 200 can produce a largeramount of radial force (defined as the radial force exerted at about 50%radial compression of a stent) than either the stent 100 or flowdiverting layer 200 alone. This higher radial force allows the duallayer stent 200 to have improved deployment and anchoringcharacteristics. In one example test of a dual layer stent embodiment,the outer stent 100 alone had an average radial force of about 0.13 N,the flow diverting layer 202 alone had an average radial force of about0.05 N and the dual layer stent 200 had an average radial force of about0.26 N. In other words, the average radial force of the stent 200 wasgreater than or equal to that of the flow diverting layer 202 and thestent 100 combined.

It should be noted that the porosity (i.e., the percentage of open spaceto non-open space) in the flow-diverting layer 202 changes as itradially expands. In this respect, a desired porosity or pore size canbe controlled by selecting different sized stents 200 (i.e., stents thatfully expand to different diameters). Table 1 below illustratesdifferent example porosities that the flow-diverting layer 202 canachieve by varying the size of the stent 200 (i.e., its fully expandeddiameter) in a particular target vessel. It should be understood thatmodifying other aspects of the flow-diverting layer 202, such as thenumber of wires used, picks per inch (PPI), or wire size may also modifyporosity. Preferably, the flow-diverting layer 202 has a porositybetween about 45-70% when expanded.

Similar techniques are also possible with regard to the porosity of thestent 100. Preferably, the stent 100 has a porosity when expanded thatis between about 75% and 95% and more preferably a range between about80% and 88%. Put a different way, the stent 100 preferably has a metalsurface area or percentage of metal between about 5% and 25% and morepreferably between 12% and 20%.

TABLE 1 Fully Expansion Porosity of Expanded Size in TargetFlow-Diverting No. of Wires PPI Stent OD (mm) Vessel (mm) Layer 202 48145 2.9 mm Fully Expanded 50% 48 145 2.9 mm 2.75 mm 56% 48 145 2.9 mm2.50 mm 61% 48 145 3.4 mm Fully Expanded 51% 48 145 3.4 mm 3.25 mm 59%48 145 3.4 mm 3.00 mm 64% 48 145 3.9 mm Fully Expanded 52% 48 145 3.9 mm3.75 mm 61% 48 145 3.9 mm 3.50 mm 67%

The stent 100 can be “oversized” or have a larger internal diameterrelative to the outer diameter of the flow-diverting layer 202 when in afully expanded position or a target vessel (having a target diameter).Preferably, the difference between the inner surface of the stent 100and the outer surface of the flow-diverting layer 202 is between about0.1 mm and about 0.6 mm (e.g., a gap between about 0.05 mm and about 0.3mm between the two). Generally, the dual layer stent 200 can be slightlyoversized for a patient's target vessel. In this respect, the outerstent 100 can slightly push into the tissue of the target vessel,allowing the “undersized” flow-diverting layer 202 to maintain a profilethat is relatively close to or even touching the tissue of the vessel.This sizing can allow the stent 100 to better anchor within the vesseland closer contact between the flow-diverting layer 202 and vesseltissue. It should be further noted that this “oversizing” of the duallayer stent 200 can result in about a 10-15% increase in the porosity ofthe flow-diverting layer 202 relative to the fully expanded (andunobstructed) position of the flow-diverting layer 202, as seen in theexample data in Table 1.

The dual layer stent 200 can provide improved tracking and deploymentperformance, especially when compared to a stent of similar size andthickness to the flow-diverting layer 202. For example, tests have shownthat a reduced amount of force is needed during deployment or retractionof the dual layer stent 200 from the delivery device in comparison to astent similar to the flow-diverting layer alone. The inclusion of theouter stent 100 as part of the dual layer stent 200 reduces friction inthe delivery system relative to the radial force and porosity of thestent 200.

Preferably, the dual layer stent 200 can be deployed or retracted withbetween about 0.2 lbs and about 0.6 lbs of force. By including the stent100 on the outside of the flow diverting layer 202, the deployment forcecan be reduced between about 10-50% as compared with thedeploying/retracting the flow diverting layer 202 alone (i.e., astandalone layer 202 used by itself as seen in FIG. 19). Since lessdeployment force is required for the dual layer stent 200 as comparedwith a bare flow diverting layer 202, more desirable deliverycharacteristics can be achieved from a deployment device.

One example deployment and retraction force test was performed on anexample dual layer stent 200 as seen in FIGS. 12-14 and a flow-divertinglayer 202 alone, as shown in FIG. 19. The dual layer stent 200 requiredan average maximum deployment force of about 0.3 lbs and an averagemaximum retraction force of about 0.4 lbs. The stent of only aflow-diverting layer 202 had an average deployment force of about 0.7lbs. Note that retraction of the flow-diverting layer 202 stent was notpossible in the tests due to a lack of a locking or release mechanism(e.g., no coils 106 to contact marker band 140, as seen in FIG. 15).Preferably, the dual layer stent 200 includes differences in thediameter of the wire 102 of the outer stent 100, similar to thosedescribed for the embodiment of FIGS. 1-10. Specifically, the wire 102making up the middle region of the stent 100 have a reduced diameterwhile the wire 102 at the ends (e.g., at loops 104) have a largerdiameter than the middle region. For example, the middle region can beelectropolished to reduce the diameter of wire 102 while the ends of thestent 100 can be protected from electropolishing, maintaining theiroriginal diameter. Put another way, the thickness of the stent 100 isthinner at a middle region. Note that this reduced thickness in themiddle region is also applicable to embodiments of the outer stent thatdo not use wire (e.g., laser cut tube stent seen in FIG. 16). In testtrials of an example embodiment of the dual layer stent 200 with thisdiameter difference, relatively low deployment and retraction forceswere demonstrated. These lower deployment and retraction forces canprovide desirable tracking, deployment and retraction characteristics.Preferably, the wires 102 of the middle region are between about 0.0003inch and about 0.001 inch smaller in diameter or thickness than thedistal and/or proximal regions of the stent 100. Preferably, the wires102 of the middle region are between about 10% to about 40% smaller indiameter or thickness than the distal and/or proximal regions of thestent 100 and most preferably about 25% smaller.

For example, one embodiment included ends composed of wire 102 having adiameter of about 0.0025 inch and a middle region composed of wire 102having a diameter of about 0.0021 inch. This embodiment averaged amaximum average deployment force of about 0.3 lbs within a range ofabout 0.2-0.4 lbs and a maximum average retraction force of about 0.4lbs within a range of about 0.3-0.4 lbs.

Another embodiment included ends composed of wire 102 having a diameterof about 0.0020 inch and a middle region composed of wire 102 having adiameter of about 0.0028 inch. This embodiment averaged a maximumaverage deployment force of about 0.2 lbs within a range of about0.2-0.3 lbs and a maximum average retraction force of about 0.3 lbs in arange of about 0.3-0.4 lbs.

Another embodiment included ends composed of wire 102 having a diameterof about 0.0021 inch and a middle region composed of wire 102 having adiameter of about 0.0028 inch. This embodiment averaged a maximumaverage deployment force of about 0.4 lbs within a range of about0.3-0.4 lbs and a maximum average retraction force of about 0.6 lbs in arange of about 0.5-0.6 inch.

Turning to FIG. 15, a delivery device 210 is shown according to thepresent invention for deploying the stent 200 within a patient. Thedelivery device 210 is generally similar to the previously describeddelivery device 135, including a sheath 133 disposed over a deliverypusher 130 to maintain the stent 200 in a compressed position overmarker band 140.

As with the previous device, a proximal end 201 of the stent 200 isdisposed over distal marker band 140 and proximal coil members 106 arepositioned between marker bands 136 and 140. The stent 200 can bedeployed by proximally retracting the sheath 201 relative to the pusher130. The stent 200 can also be retracted (if it was not fullydeployed/released) by retracting the pusher 130 in a proximal direction,thereby causing the marker band 140 to contact the proximal coil members106, pulling the stent 200 back into the sheath 133.

As previously described, the proximal end 201 of the stent 200 includesattachment members 206 (not shown in FIG. 15) which connect the stent100 with the flow-diverting layer 202. In this respect, as the sheath133 is proximally retracted during deployment and a distal portion 203of the dual layer stent 200 begins to radially expand, the stent 100 andthe flow-diverting layer 202 can decrease in length at different rates.

A portion of the wire 105 can be woven along the length of the stent 100in a distinctive pattern. This length can correspond to the length andposition of the inner flow diverting layer 202, thereby indicating thelength and position of the inner flow diverting layer 202 to the userduring a procedure.

In another preferred embodiment according to the present invention, theflow-diverting layer 202 may be woven into the anchoring stent 100.

FIG. 16 illustrates another embodiment according to the presentinvention of a dual layer stent 300 comprising an inner flow-divertinglayer 202 and an outer stent 302. Preferably, the outer stent 302 isformed by cutting a pattern (e.g., laser cutting or etching) in a sheetor tube composed of a shape memory material (e.g. Nitinol). FIG. 16illustrates a pattern of a plurality of diamonds along the length of theouter stent 302. However, it should be understood that any cut patternis possible, such as a plurality of connected bands, zig-zag patterns,or wave patterns.

The cross sectional view of the dual layer stent 300 illustrates aplurality of example positions for attachment member 206 to connect theouter stent 302 and inner flow-diverting layer 202. As with any of thepreviously described embodiments, the attachment members 206 (or othermethods of attachment such as welding or adhesive) can be located at oneor more of the example locations shown. For example, attachment members206 may be located at the proximal end, distal end, or the middle. Inanother example, attachment members 206 can be located at both theproximal and distal ends. Alternately, no attachment members 206 orattachment mechanism are used to attach the inner flow-diverting layer202 with the outer stent 302.

FIG. 18 illustrates another embodiment of a dual layer stent 400according to the present invention. The stent 400 comprises an innerflow-diverting layer 202 attached to an outer stent 402. The outer stent402 comprises a plurality of radial, zigzag bands 404 that are bridgedor connected via longitudinal members 406. Preferably, the stent 402 canbe created by welding a plurality of members together, laser cutting oretching this pattern into a sheet or tube, or using vapor depositiontechniques. As with previous embodiments, the flow-diverting layer 202can be attached to the outer stent 402 near the distal end, proximalend, middle region, or any combination of these locations.

As best seen in FIGS. 12 and 13, the flow-diverting layer 202 preferablyhas a length that extends near the ends of the main body portion ofstent 100 and stops near the formation of the loops 104. However, theflow-diverting layer 202 can alternately include any range of lengthsand positions relative to the stent 100. For example, FIG. 20illustrates a dual layer stent 200A in which the flow-diverting layer202 is shorter in length than the stent 100 and longitudinally centeredor symmetrically positioned.

In another example, FIG. 21 illustrates a dual layer stent 200B in whichthe flow-diverting layer 202 is longer in length than the stent 100.While the flow-diverting layer 202 is shown as being longitudinallycentered within the stent 100, asymmetrical positioning of theflow-diverting layer 202 is also contemplated.

In yet another example, FIG. 22 illustrates a dual layer stent 200C inwhich a flow-diverting layer 202 is shorter in length than the stent 100and asymmetrically positioned within the stent 100. In this example, theflow-diverting layer 202 is positioned along the proximal half of thestent 100, however, the flow-diverting layer 202 may also be positionedalong the distal half of the stent 100. While the flow-diverting layer202 is shown extending about one half of the length of the stent 100,the flow-diverting layer 202 may also span one third, one quarter or anyfractional portion of the stent 100.

Turning to FIGS. 23-25, the flow-diverting layer 202 can be composed ofone or more expansile wires 500 or filaments. Preferably, the expansilewires 500 are composed of the previously described wires 204 that arecoated with a hydrogel coating 502 that expands in a patient's vessel.The wires 204 may be composed of a shape memory metal (e.g., nitinol), ashape memory polymer, nylon, PET or even entirely of hydrogel. As seenin FIG. 25, the hydrogel wires 500 can be woven amongst wires 204 whichare not coated with hydrogel. Alternately, partial lengths of the wirescan be coated with hydrogel so as to coat only a specific region of theflow-diverting layer 202 (e.g., the center region).

In any of the previous embodiments, one or more of the stent layers(e.g., stent 100 or flow diverting layer 202) can be mostly composed ofa polymer (e.g., a hydrogel, PET (Dacron), nylon, polyurethane, Teflon,and PGA/PGLA). Generally, a polymer stent can be manufactured by thefree radical polymerization of a liquid prepolymer solution within acontainer of a desired shape.

One example polymer stent manufacturing technique can be seen in FIGS.26-29. Starting with FIG. 26, a generally cylindrical mandrel 602 isplaced within a tube 600. Preferably, the mandrel 602 can create afluid-tight seal on at least one end of the tube 600 and preferably theopposing end of the tube 600 is also closed.

In FIG. 27, a liquid prepolymer is injected into the space between themandrel 602 and the tube 600. Polymerization is induced in theprepolymer solution (e.g., heating at 40-80° C. for 12 hours). Oncepolymerized, the tube 600 and mandrel 602 are removed from the solidpolymer tube 606, shown in FIG. 28. This tube 606 can be washed toeliminate residual monomers and dried over a mandrel to maintain shape.

Finally, the polymer tube 606 can be laser cut, CNC machined, etched orotherwise shaped into a desired pattern, as seen in FIG. 29. The lengthand thickness of the final stent can also be modified during themanufacturing process by changing the diameter or length of the tube 606or the mandrel 602.

In another example stent manufacturing process seen in FIG. 30,centrifugal force is used to disperse the prepolymer solution along theinside of a syringe tube 605. Specifically, a plunger 603 is positionedin the tube 605 and a predetermined amount of prepolymer solution 604 istaken into the syringe tube 605. The syringe tube 605 is connected to amechanism that causes the tube 605 to spin in a horizontal orientationalong a longitudinal axis of the tube 605 (e.g., an overhead stirrerpositioned horizontally with its rotating member connected to the tube605).

Once the tube 605 achieves a sufficient rotational speed (e.g., about1500 rpm), the syringe plunger 603 is pulled toward the end of the tube605, taking in a gas such as air. Since the prepolymer solution now hasmore space to spread out, the centrifugal force causes an even coatingto form on the wall of the tube 605. Polymerization can be initialedusing a heat source (e.g., a heat gun) and then heated (e.g., 40-80° C.for 12 hours). The solid polymer tube can then be removed from the tube605, washed to eliminate residual monomers, dried on a mandrel, and thenlaser cut, CNC machined, etched or otherwise shaped into a desiredpattern.

FIGS. 31-36 illustrate yet another example process for creating apolymer stent according to the present invention. Turning first to FIG.31, a plastic or degradable rod 608 is placed in tube 600 and lueradapters 610 are connected to each opening of the tube 600. The rod 608has an engraved or depressed pattern (e.g., created by laser machining,CNC machining or other suitable method) on its outer surface in thepatter desired for the final stent. When the rod 608 is placed in thetube 600, these patterns form channels that are later filled by theprepolymer 604. In other words, the outer diameter of the rod 608 andthe inner diameter of the tube 600 are such that the prepolymer 604 isprevented from moving outside the channels or patterned area.

As seen FIG. 32, a syringe 612 is inserted into a luer adapter 610 andprepolymer solution 604 is injected into the tube 600 as seen in FIG.33. The prepolymer solution 604 fills into the pattern on the surface ofthe rod 608. The syringe 612 is removed from the luer adapter 610 andpolymerization is completed by heating the prepolymer solution 604(e.g., 40-80° C. for about 12 hours).

The rod 608 is removed from the tube 600 as seen in FIG. 34 and placedin an organic solvent bath 622 as seen in FIG. 35. The organic solventbath 622 dissolves the rod 608, leaving only the polymer stent 622 (FIG.36) having the same pattern as the surface of the rod 608.

It should be noted that different aspects of the stent 622 can becontrolled by changing the pattern on the surface of the rod 608, thediameter of the rod 608 and the tube 600, the length of the rod 608 andtube 600 and similar dimensions. Additional modification is alsopossible by laser cutting, CNC machining, etching, or similar processes.

FIGS. 37-50 illustrate various modifications of delivery pusher 130which have been previously described in this embodiment. Some of theembodiments include a friction region of larger diameter near a distalend of the pusher to prevent the stent from over compressing and createsfriction between the stent and pusher to help push the stent out of thecatheter sheath. Additionally, when the friction region is in contactwith the inner surface of the stent, it allows the physician to pull thestent out of the delivery sheath rather than pushing on the stent fromits proximal end. Hence, the stent may require less rigidity.Furthermore, the friction region distributes the deployment force fromthe pusher over a greater surface area of the stent, thereby reducingstress on the stent that can result from pushing or pulling on the stentat a single location. This distribution of force makes the deliverysystem more reliable since the strength of the bond between the deliverypusher and the friction region can be lower than would be otherwiserequired if the stent was pushed or pulled from a single location.Including the friction region with pushing or pulling features of themarker bands also creates a redundancy for both advancing the stent ourof the catheter or retracting the stent back into the catheter, since ifone mechanism fails, the other would allow the physician to complete theprocedure.

In FIGS. 37-39, the pusher 700 includes several tapered or conicalregions between the marker bands 136 and 140. Specifically, the pusher700 includes two regions of UV adhesive: a distal region 708 at thedistal end of the coiled distal tip member 144 and a tapered or conicalregion 704 at the proximal end of the tip member 144. The second markerband 140 includes a distal tapered region 702 composed of epoxy (e.g.,EPOTEK 353). The proximal face of marker band 140 and the distal face ofmarker band 136 include a small amount of epoxy 706 that is shaped to aslight taper or conical shape. The marker bands 136 and 140 and coiledtip member 144 are preferably composed of platinum. The core wire 132 ispreferably composed of Nitinol and the coil 134 is preferably composedof stainless steel. In one example, the distance between markers 136 and140 is about 0.065, the distance between marker 140 and conical region704 is about 0.035 cm, and the coiled tip is about 0.100 cm in length.

In the pusher embodiment 710 of FIG. 40, an elongated polymer region 712(e.g., PET, Teflon, Pebax, nylon, PTFE) is located on section 142 of thecore member 132 between the distal marker band 140 and the distal tip144. This polymer region 712 can be formed from a shrink tube having athickness of about 0.00025 inches or from braided polymer strands. Oneadvantage of the polymer region is that it adds some thickness to thecore wire and thereby prevents the stent (which is compressed on top)from over-compressing or collapsing when advanced through highlytortuous vessels of a patient.

FIG. 41 illustrates a pusher embodiment 714 having a plurality of spacedapart sections 716 having a diameter that is larger than that of thecore wire. These sections can be composed of polymer (e.g., shrink tubeor braiding) or from a non-polymer material. A portion of the core wire718 can be pre-shaped to have a plurality of curves or a wave shape. Thewave region and material sections may prevent the stent fromover-compressing during tortuous passage through a vessel. Additionally,the wave shapes may help force open a stent as it is delivered from thecatheter. More specifically, the wave shape may be relatively straightwhen a stent is compressed over the wave shape in the delivery device,but expands as it exits the catheter, forcing the stent open. This stentexpansion may be especially important when delivering the stent to acurved or bent vessel where the physician would typically push thedelivery system forward to assist in causing the stent to open. In thisrespect, the delivery system would be less operator-dependent since thedelivery system would pushed open automatically by the pusher 714. Byincluding multiple material sections 716, the curves of the wave regionmay be better retained when expanded as compared to a single elongatedpolymer section (e.g., FIG. 41).

FIG. 42 illustrates a pusher embodiment 720 having an elongated polymerregion 712 similar to the embodiment of FIG. 40 and a wave region 718similar to the embodiment of FIG. 41. FIG. 43 illustrates a pusherembodiment 722 having multiple polymer areas 716 similar to theembodiment of FIG. 41 and a generally straight core wire 142 at thedistal end of the pusher, similar to that of FIG. 40.

FIG. 44 illustrates a pusher embodiment 724 having an elongated straightregion with a polymer region similar to the embodiment of FIG. 40.However, this polymer region extends the entire length between thedistal marker band 140 and the distal tip 144.

FIG. 45 illustrates a pusher embodiment 726 forming a closed loopbetween the distal marker band 140 and the distal tip 144 of the pusher726 (i.e., an aperture in region 142 of the core member). This loop mayprevent the stent from collapsing or over-compressing on the pusher,especially when advanced through tortuous vessels. Preferably, this loopis formed by welding both ends of a Nitinol wire 728 to an area 730 ofthe pusher's core wire. Both the attached wire 728 and the area of thecore wire 730 can be bent or angled at each end to form an elongatedloop shape of varying sizes. In this regard, the core member forms twoopposing, branching shapes who's arms connect together to form anaperture or loop.

FIG. 46A illustrates a pusher embodiment 732 having a generally straightdistal end 142 that terminates in a pigtail shape 734. The pigtail shape734 can be created by bending the core wire 142 in several differentorientations, as seen in FIG. 46A. For example, the pigtail shape 734Bcan be symmetrically positioned on the core wire (FIG. 46C) orasymmetrically offset 734A in one direction (FIG. 46B). This pigtailedshape helps to resist the stent from collapsing or over-compressing,thus aiding in the deployment and retrieval of the device.

FIG. 47 illustrates a pusher 736 with a spiral or coil region 738 formedfrom a plurality of loops 739 near its distal end. The spiral region mayencompass all exposed areas of the core wire or a fractional length. Thepusher 740 of FIG. 48 illustrates a coil region 142 in which some loops744A are relatively close together, while other loops 744B have a largerspacing from each other. Additionally, the spiral region 748 of pusher746 in FIG. 49 may include a continuous or segmented coating or jacket750 along its length or adjacent to the spiral region (e.g., PET,Teflon, Pebax, nylon, PTFE). Similar to previous embodiments, the spiralregion increases the diameter of the pusher's distal end and therebyprevents the stent from collapsing or over compressing. However, sincethe spiral region's effective diameter increase of the pusher can beachieved without necessarily increasing the diameter of the core wire,flexibility of the pusher is generally similar to embodiments withstraight distal core wires. The spiral region 754 of pusher 752 may alsovary in diameter or pitch (e.g., increasing pitch, decreasing pitch, ordiscrete sections of different diameters) as seen in FIG. 50 and ispreferably selected based on based on the shape, size and properties ofthe stent.

FIGS. 51-59 disclose an embodiment of a rapid exchange delivery device770 for delivering a stent 793. While this delivery device 770 may beused for a variety of locations, it may be particularly useful fordelivering stents in the carotid arteries for treatment of peripheralartery disease.

Turning first to FIG. 51, the device 770 includes a pusher member 772having an elongated core member 776 that slides within a catheter 774,through proximal catheter port 780. Preferably, the proximal end of thecore wire includes a handle 778 for facilitating movement of the pushermember 772 relative to the catheter 774.

Instead of providing a guide wire passage that extends throughout theentire length of the catheter 774, the catheter 774 preferably includesa shortened “rapid exchange” passage in which the guide wire 786 onlypasses through a relatively short, distal portion of the catheter 774(e.g., 5-10 inches). Once a distal end of the guide wire 786 ispositioned near a target location, the proximal end of the guide wire786 is inserted into a rapid exchange port 794A of a distal guide wiretube 794, as seen in FIG. 58. As seen best in FIGS. 55-57, the proximalend of the guide wire 786 passes through the distal guide wire tube 794and into catheter tube 788. Finally, as best seen in FIG. 53, the guidewire 786 exits tube 788, passes through a remaining portion of the outercatheter tube 782, and exits the catheter at rapid exchange port 784.

Returning to FIGS. 55-57, the distal guide wire tube 794 extends intocatheter tube 788 in a telescoping arrangement. Preferably, the distalguide wire tube 794 extend into the catheter tube 788 by at least thesame distance the catheter 774 is retracted relative to the pusher 772.In this respect, the distal guide wire tube 794 and the catheter tube788 maintain a continuous passage for the guide wire 786, even as thecatheter 774 is retracted relative to the pusher 772 to release thestent 793.

As best seen in FIGS. 54-57, a distal end of the core member 776includes an anchor member 792 for anchoring and retracting the stent 793during deployment. The anchor member 792 includes a body 792A that formsa backstop surface 792D against which the stent 793 can be pushed.

The stent 793 preferably includes a plurality of proximal loops that fitover a plurality of radially oriented posts 792C when the stent 793 iscompressed on the pusher as seen in FIG. 54. For example, the stent 793may have three loops and the anchor member 792 may have three posts 792Cfixed at equidistant radial intervals from each other. During stentdeployment, a physician may wish to retract the stent 793 so that it canbe repositioned. As the pusher 772 is retracted or the catheter 774 isadvanced, the posts 792C pull or anchor the end of the loops, causingthe stent 793 to be pulled back into the outer tube 782 of the catheter774.

In one embodiment, the posts 792C each have a generally flat distalsurface and two angled or rounded proximal surfaces. In anotherembodiment seen in FIG. 59, the anchor 793 includes posts 793C havingboth distal and proximal surfaces that are angled toward each other(i.e., similar to a pyramid with a flat top surface).

Returning to FIGS. 54-57, the anchor 792 includes an elongateddepression 792B that is sized to contain the core member 776. A distalend of the core member 776 is fixed in the depression 792B via knownmethods, such as welding or adhesives. As previously discussed, the coremember passes through a core member passage 787 in the catheter 774,exits out of proximal port 780 and terminates with handle 778 on itsproximal end. Hence, the core member 776 directly connects the anchor792 and therefore the stent 793 to the handle 778, providing direct,positive, tactile feedback to the physician. Preferably, the anchor 792is composed of metal to further enhance the tactile feedback felt by thephysician.

FIG. 60 illustrates another embodiment of a delivery pusher 130 that isgenerally similar to the delivery pusher 130 in FIGS. 7 and 8. However,delivery pusher 800 includes a third, middle marker band 137 locatedbetween marker bands 136 and 140. Preferably, the marker band 137 has adiameter similar to that of marker band 140 and is somewhat smaller indiameter than marker band 136. The stent 100 is preferable compressedover both markers 137 and 140 such that the proximal coils 106 of thestent 100 are positioned between and closely associated with the twomarkers 137 and 140. During deployment of the stent 100, a physician maywish to advance the pusher 800 relative to the outer catheter sheath133. In this regard, the marker 137 distally pushes on the coils 106 ata location that may reduce the tendency of the stent 100 to buckle.

FIG. 61 illustrates another embodiment of a delivery pusher 802 that issimilar to the previously described pusher 800. However, the pusher 802also includes a marker 139 positioned near the coiled distal tip member144. Preferably, the marker 139 is spaced proximally from the distal tipmember 144 so as to allow space for the distal coils 106 of the stent100. During stent deployment, the marker 139 may contact the distalcoils 106 if the pusher 802 is advanced relative to the catheter sheath133. In this regard, the marker 139 may be configured to initially pushon the distal coils 106 until the distal end of the stent 100 exits thecatheter sheath 133 and expands. From there, the marker 137 may push onproximal coils 106 until the remaining portion of the stent 100 has beenpushed out of the catheter sheath 133.

In yet another embodiment similar to FIG. 61, the pusher may includemarkers 139, 140 and 136. In this respect, advancing the pusher relativeto the sheath 133 may push the distal coils 106 and distal end of thestent 100 out of the catheter sheath 133.

It should be noted that one or more of any of the markers 136, 137, 139,and 140 from the previously described embodiments may alternately becomposed of a non-radiopaque material. Additionally, one or more of anyof the markers 136, 137, 139, and 140 from the previously describedembodiments may be removed.

FIG. 62 illustrates an embodiment of a flow diverting stent 810 which issimilar to the stent 200 shown in FIGS. 12-14, including an outeranchoring stent layer 100 having six loops 104 on each of its distal andproximal ends, and a flow-diverting layer 202 that is located within theinner lumen or passage of the anchoring stent layer 100. However, theouter anchoring stent layer 100 and inner flow-diverting layer 202 arewoven or braided so that their wires 102 and 204 have substantially thesame pitch.

Woven stent layers tend to increase in length as they compress anddecrease in length as they expand. When two woven stent layers havedifferent pitches of braiding, the layer with the higher pitch typicallyelongates further and faster than a similarly sized layer having arelatively lower pitch braid. Therefore, to expand correctly, stentlayers with different braid pitches can typically be attached at onlyone end of the stent.

In contrast, the layers 100, 202 of stent 810 have the same braid pitchwhich allows each layer to radially compress to the same increasedlength at the same rate, from similar expanded shapes, or radiallyexpand to the same decreased length at the same rate. In other words,the layers 100, 202 maintain similar positions relative to each other asthey simultaneously expand or contract. Since the layers 100, 202 remainin relatively the same positions in relation to each other, the layerscan be constructed such that they have substantially no clearancebetween each other. This lack of clearance between layers may reduce oreven prevent collapsing or buckling of the inner flow-diverting layer202 within tortuous vessels. In one example, both the outer anchoringlayer 100 and inner flow-diverting layer 202 may have a woven pitch of40, 45, or 50 picks per inch.

As previously discussed, the layers 100, 202 of the stent 810 can beconstructed to have substantially no clearance or gap between them. Inaddition to matching the pitch of the layers 100, 202, this closeassociation of layers can be achieved by braiding and heat-setting theinner flow-diverting layer 202 on a rod or mandrel to have an outerdiameter that is equal to the inner diameter of the inner diameter ofthe outer anchoring layer 100. This sizing provides a line to line fitof both layers, which can prevent physiological reactions likethrombosis.

The close association of the layers 100, 202 can be further maintainedby including one or more additional support wires 814 that are woventhrough both layers. For example, each end of a tantalum support wire814 can be coiled around wire 102 near a distal and proximal end of thestent 810 and woven between the layers, as seen in FIG. 62 and themagnified areas of FIGS. 63 and 64.

In the present example embodiment, three different support wires 814 arewoven in a generally helical pattern through both layers 100, 202. Forexample, starting at one of the coils 816, the support wire 814generally follows the curvature and position of each wire 102. As seenin FIG. 65, at areas where the wire 102 crosses over another portion ofitself (i.e., radially outward), the support wire 814 follows a similarpath over the crossing portion of wire 102, as well as over wires 204(e.g., the area at 820). As seen in FIG. 66, at areas where the wire 102passes underneath another portion of itself (i.e., radially inward), thesupport wire 814 also passes underneath the intersecting region of wire102, but also further passes underneath the next intersecting wire 204,shown at area 822. Preferably, the pattern of FIG. 65 followed by FIG.66 alternate with each other along the length of the stent 810. In thisrespect, the support wire 814 creates a radial shape that passesunderneath wires 202 at regular intervals, thereby maintaining the twolayers 100 and 202 against each other. By providing this additionalsupport to maintain the layers, the stent 810 may particularly maintainthe close association of layers 100 and 202 when deployed an a curved ortortuous vessel, such as a carotid artery.

In the present example embodiment, three support wires 814 extendsubstantially the entire length of the stent 810 and have equal radialspacing from each other. However, any number of support wires 814 can beused, such as 1, 2, 3, 4, 5, 6, 7, 8, 9. In another example embodiment,each support wire may extend from a location substantially near an endof the stent to a middle region of a stent, forming two sets of supportwires 814 on each side of the stent 810. In another example embodiment,each support wire 814 may extend between each end of the stent 810, butmay also include additional areas where the support wire 814 is coiled,such as at a middle region of the stent 810.

FIG. 67 illustrates another embodiment of a stent 830 having a singlelayer braided from larger wires 102 and smaller wires 204 that can havedifferent sizes as described elsewhere in this specification. The wires102 and 204 are preferably braided at the same braid angle, allowingthem to expand and contract as similar rates and lengths. Preferably,all wires 102, 204 are woven according to the same braid pattern and thelarger wire 102 is preferably separate by several wires 204 (e.g., eachwire 102 is followed and preceded by 3 or 6 wires 204).

One advantage of this single layer stent 830 is that is can be braidedon a braiding machine, rather than having portions or layers that arebraided by hand. Unlike the previously described embodiments thatutilize the single-wire stent layer 100, the single layer stent 830 mayinclude multiple free ends of wires 102 after an initial braiding. Sincethese larger wires may have a tendency to curl and/or unravel, the freeends are preferably fixed together via welding, coils, tubes, adhesives,or similar methods. The free ends of wires 204 can be left free sincethey may not curl or unravel to the same extent as wires 102, or theends of wires 204 can be similarly fixed or welded together. The stent830 can be cylindrical or can be braided or heat-set to have a taperedshape.

It should be noted that any of the aspects of each stent or deliverysystem embodiment described in this specification can be combined withother aspects of other stent or delivery system embodiments described inthis application. Therefore, while specific stent and delivery systemembodiments have been shown, other combinations are contemplated inaccordance with the present invention.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. A device comprising: a first layer formed from asingle shape memory metal wire and having a first porosity and forming agenerally tubular shape with a space therethrough; a second layer formedfrom shape memory metal wire and having a second porosity that is lowerthan said first porosity; said second layer located within said spacewithin said tubular shape; wherein said second layer is connected tosaid first layer at one or more locations.
 2. The device of claim 1wherein the second porosity is between 45% and 70%.
 3. The device ofclaim 1, further comprising a support wire woven to connect said firstlayer to said second layer at said one or more locations along saidlength of said device.
 4. The device of claim 3, wherein said supportwire is woven is woven in a helical pattern.
 5. The device of claim 3,wherein a proximal end of said support wire and a distal end of saidsupport wire are each coiled around portions of said first layers. 6.The device of claim 1, wherein said one or more of locations along saidlength of said device includes a distal end of said device and aproximal end of said device.
 7. The device of claim 3, furthercomprising a second support wire and a third support wire helicallywoven to connect said first layer to said second layer at said one ormore locations along said length of said device.
 8. The device of claim1, further comprising a first support wire woven to connect said firstlayer to said second layer near a first end and a middle of said device;and a second support wire woven to connect said first layer to saidsecond layer near a first end and a middle of said device.
 9. The deviceof claim 1, wherein said first layer and said second layer havesubstantially the same braid pitch.
 10. The device of claim 1, whereinsaid first layer and said second layer have substantially no gap betweenthem.
 11. The device of claim 1, wherein the first layer and the secondlayer have substantially the same pitch and substantially no clearancebetween the layers.
 12. The device of claim 11, wherein said secondlayer is braided and heat-set to have a diameter equal to an innerdiameter of said first layer.
 13. The device of claim 11, wherein saidfirst layer and said second layer have substantially the same braidpitch.
 14. The device of claim 11, wherein said first layer and saidsecond layer expand at substantially the same rate and foreshorten bysubstantially the same amount.
 15. The device of claim 11, wherein saidfirst layer and said second layer are attached to each other near aproximal end of said device and at a distal end of said device.
 16. Thedevice of claim 11, wherein said first layer and said second layer areattached to each other by a support wire woven between said first wovenlayer and said second woven layer in a helical pattern.